An image forming apparatus such as a copying machine contains a replaceable toner cartridge that supplies toner to the apparatus through a toner supply port in the cartridge. Because of the agglutinous texture of the toner, many cartridges contain both rotary mixers to ensure mixing and even distribution of the toner within the cartridge as well as an auger or other delivery mechanism that delivers toner to the toner supply port. Toner that is delivered to the toner supply port is pushed, pulled, or falls by gravity, through the supply into an adjacent port in the image forming apparatus. However, because standard augers do not seal the supply port, toner can leak through the supply port and into the apparatus, thereby delivering toner in an unregulated fashion. Excess toner can result in toner overload, clogging of the apparatus, a decrease in image quality, and/or apparatus failure. Some cartridge systems have attempted to address this problem, such as cartridges described in U.S. Pat. No. 6,229,976; U.S. Pat. No. 6,091,920; U.S. Pat. No. 6,128,453; and U.S. Pat. No. 6,542,709, but these devices require additional seal or gear components that are prone to failure or do not provide a consistent amount of toner. As a result, the quantity of toner being delivered to the machine is not consistent, making the cartridges on the market unreliable.
A need therefore exists for a toner cartridge that provides a reliable and consistent supply of toner to an image forming apparatus at an optimum and steady feed rate, while preventing the free flow of toner out of the toner supply port of the cartridge.